The invention relates to additives for inorganic cements. In particular, the invention relates to a retarder or setting control for alkali-activated silicate cements or binders.
Alkali-activated glass-based binders have very rapid set times. In some circumstances, the set time is so short that the materials cannot be used for some applications in general construction. For some compositions, the time to initial set is often less than 60 minutes making it difficult to mix, place and finish.
The alkali-activated cements have been extensively studied and are well known in the art. Indeed, one of the important features of alkali-activated materials is that they tend to set up and cure to relatively high strengths in a matter of hours. This is useful in military applications, for example, runway repair. However, as noted above, the initial set of these materials is sometimes so rapid that the material can cure in the mixing apparatus creating serious and costly maintenance problems.